CVE-2023-54006
Description
In the Linux kernel, the following vulnerability has been resolved:
af_unix: Fix data-race around unix_tot_inflight.
unix_tot_inflight is changed under spin_lock(unix_gc_lock), but unix_release_sock() reads it locklessly.
Let's use READ_ONCE() for unix_tot_inflight.
Note that the writer side was marked by commit 9d6d7f1cb67c ("af_unix: annote lockless accesses to unix_tot_inflight & gc_in_progress")
BUG: KCSAN: data-race in unix_inflight / unix_release_sock
write (marked) to 0xffffffff871852b8 of 4 bytes by task 123 on cpu 1: unix_inflight+0x130/0x180 net/unix/scm.c:64 unix_attach_fds+0x137/0x1b0 net/unix/scm.c:123 unix_scm_to_skb net/unix/af_unix.c:1832 [inline] unix_dgram_sendmsg+0x46a/0x14f0 net/unix/af_unix.c:1955 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg+0x148/0x160 net/socket.c:747 ____sys_sendmsg+0x4e4/0x610 net/socket.c:2493 ___sys_sendmsg+0xc6/0x140 net/socket.c:2547 __sys_sendmsg+0x94/0x140 net/socket.c:2576 __do_sys_sendmsg net/socket.c:2585 [inline] __se_sys_sendmsg net/socket.c:2583 [inline] __x64_sys_sendmsg+0x45/0x50 net/socket.c:2583 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x3b/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x72/0xdc
read to 0xffffffff871852b8 of 4 bytes by task 4891 on cpu 0: unix_release_sock+0x608/0x910 net/unix/af_unix.c:671 unix_release+0x59/0x80 net/unix/af_unix.c:1058 __sock_release+0x7d/0x170 net/socket.c:653 sock_close+0x19/0x30 net/socket.c:1385 __fput+0x179/0x5e0 fs/file_table.c:321 ____fput+0x15/0x20 fs/file_table.c:349 task_work_run+0x116/0x1a0 kernel/task_work.c:179 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline] exit_to_user_mode_loop kernel/entry/common.c:171 [inline] exit_to_user_mode_prepare+0x174/0x180 kernel/entry/common.c:204 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline] syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:297 do_syscall_64+0x4b/0x90 arch/x86/entry/common.c:86 entry_SYSCALL_64_after_hwframe+0x72/0xdc
value changed: 0x00000000 -> 0x00000001
Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 4891 Comm: systemd-coredum Not tainted 6.4.0-rc5-01219-gfa0e21fa4443 #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
A data-race in the Linux kernel's af_unix module was found in the handling of `unix_tot_inflight`, addressed by adding READ_ONCE().
Description
A data-race vulnerability exists in the Linux kernel's af_unix module affecting the unix_tot_inflight counter. The counter is updated under spin_lock(unix_gc_lock), but unix_release_sock() reads it without any synchronization. This mismatch was detected by the Kernel Concurrency Sanitizer (KCSAN) and can lead to unpredictable behavior if the read observes a stale or partially updated value [1].
Exploitation
Exploitation requires a multi-threaded or multi-process environment where one thread or process triggers unix_release_sock() while another concurrently performs unix_inflight() (e.g., via unix_dgram_sendmsg()). No special privileges beyond the ability to create and use Unix domain sockets are needed, as the race is inherent to the kernel code [2].
Impact
A successful data-race could cause unix_tot_inflight to be incorrectly read, potentially leading to incorrect garbage collection decisions. In practice, this may result in resource leaks or premature reclamation of in-flight file descriptors, though the exact impact depends on timing and system state.
Mitigation
The fix applies READ_ONCE() to reads of unix_tot_inflight, aligning with the already marked writer side (commit 9d6d7f1cb67c). The patch is backported to stable kernel trees [3]. No workaround exists apart from updating to a patched kernel version.
AI Insight generated on May 19, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.
Patches
831b46d5e7c4e20aa8325464d5d91b7891f4acf29b42766ade5edc6e44a882d8933ca863eafc284a4a781ade32bd8a738Vulnerability mechanics
Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.
References
8- git.kernel.org/stable/c/20aa8325464d8905450089eed96ca102a074d853nvd
- git.kernel.org/stable/c/2d8933ca863e252fb09ad0be483255e3dfeb1f54nvd
- git.kernel.org/stable/c/31b46d5e7c4e295bd112960614a66a177a057dcanvd
- git.kernel.org/stable/c/5d91b7891f4a9a9d69d75e9f44ab4bf1f3b11840nvd
- git.kernel.org/stable/c/ade32bd8a738d7497ffe9743c46728db26740f78nvd
- git.kernel.org/stable/c/afc284a4a781defbb12b2a40427fae34c3d20e17nvd
- git.kernel.org/stable/c/cf29b42766ad4af2ae6a449f583796951551b48dnvd
- git.kernel.org/stable/c/e5edc6e44a882c0458878ab10eaddfe60ac34e57nvd
News mentions
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